Joint USAF/NOAA Report of Solar and Geophysical Activity 21 May 2008

Product: Report of Solar-Geophysical Activity
Issued: 2008 May 21 2200 UTC
Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Weather Prediction Center and the U.S. Air Force.

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 142 Issued at 2200Z on 21 May 2008

IA. Analysis of Solar Active Regions and Activity from 20/2100Z to 21/2100Z: Solar activity was very low. The visible disk is spotless.

IB. Solar Activity Forecast: Solar activity is expected to be very low.

IIA. Geophysical Activity Summary 20/2100Z to 21/2100Z: The geomagnetic field was mostly unsettled. An isolated active period was observed at 21/0300 – 0600Z. Solar wind speed increased gradually from approximately 450 km/s to values ranging between 550 – 620 km/s. The solar wind signatures were consistent with a high speed stream from a coronal hole.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be unsettled with a chance for isolated active periods for the next three days (22 – 24 May) due to persistent effects from the high speed stream.

III. Event Probabilities 22 May-24 May

• Class M 01/01/01
• Class X 01/01/01
• Proton 01/01/01
• PCAF Green

• IV. Penticton 10.7 cm Flux
• Observed 21 May 069
• Predicted 22 May-24 May 068/068/068
• 90 Day Mean 21 May 071

V. Geomagnetic A Indices

• Observed Afr/Ap 20 May 007/010
• Estimated Afr/Ap 21 May 015/015
• Predicted Afr/Ap 22 May-24 May 008/015-008/010-008/010

VI. Geomagnetic Activity Probabilities 22 May-24 May

A. Middle Latitudes

• Active 25/25/25
• Minor storm 10/10/10
• Major-severe storm 01/01/01

B. High Latitudes

• Active 40/40/40
• Minor storm 20/20/20
• Major-severe storm 10/10/10